<template>
  <div class="spec-preview">
    <img ref="img1" :src="skuInfo.skuDefaultImg" />
    <!-- 给小图添加事件实现放大镜效果 -->
    <div class="event" @mousemove="move"></div>
    <div class="big">
      <img ref="img2" :src="skuInfo.skuDefaultImg"  
        :style="{left:-2*left+'px',top:-2*top+'px'}"
      />
    </div>
    <div class="mask"
        :style="{left:left+'px',top:top+'px'}"
    >
      
    </div>
  </div>
</template>

<script>
  import {mapGetters} from "vuex";
  import _ from 'lodash';
  export default {
    name: "Zoom",
    computed: {
      ...mapGetters("detail",["skuInfo"])
    },
    data(){
      return {
        left:0,
        top:0
      }
    },
    methods:{
      //防抖操作:以最后一次结果为准——.debounce
      //节流会以固定频率触发事件 _.throttle
      move:_.throttle( function (e){
        let x = e.offsetX - 100;
        if(x<0)  x=0 ;
        if(x>200) x=200;
        let y = e.offsetY - 100;
        if(y<0) y=0;
        if(y>200) y= 200;
        this.left = x;
        this.top = y;
      },1000/60)
     
      
    }
  }
</script>

<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>